It looks like this might be quite a long list.
The only ones that immediately came to mind were these:
NetbootCD - for downloading and booting various linux distros from one boot CD.
PiCorePlayer - Audio server software based on PiCore.
However then I tried searching for
core.gz and
corepure64.gz at GitHub using DuckDuckGo (searching at GitHub directly didn't seem to work). This seems to unlock waves of TC-based projects, and I didn't even dig all that deep into the results:
llnux-clone - Tool to clone an install of a linux distribution.
wsl-tcl-setup - A script that allows Tiny Core Linux to run on WSL 2 (Windows Subsystem for Linux).
Tiny Core for PC Engines APU embedded system board - A neat x86-based Single Board Computer (SBC).
Frix - IBM PC Compatible SoC for a commercially available FPGA board (in other words: A 486-based PC running inside a custom-programmable chip; an open-source PC implementation).
EvilAbigail - Automated Linux evil maid attack (hacking into other Linux distros to steal passwords).
SmuggleBus - Bootable USB for hacking Windows installations.
Virtual Tiny Core - Create a Tiny Core based virtual machine.
On-Prem seem to use tweaked Tiny Core stuff heavily for their commercial "virtual appliance" building service.
U-Root - Go-based software environment, supports Tiny Core extensions so I guess TC-inspired if not actually based on TC.
Developed by Google, Facebook, and Oracle!
Overall Tiny Core based projects seem to be a lot more innovative than the average derived Linux distro. It's a pretty interesting topic to look into.
I also have a project based on PiCore that I'm working on, but there's no info about the Tiny Core side of it online yet and I haven't had time/energy to work on it for a little while.